JP3372145B2 - Pipe clamp device for measurement in reactor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling water reactor (B).
TECHNICAL FIELD The present invention relates to a piping clamp device for measuring pipes in a reactor used for reducing stress caused by fluid vibration generated at a welded portion of a support connecting a diffuser of a jet pump and a measuring pipe installed in a reactor pressure vessel of a WR. Conventionally, in a boiling water reactor, a recirculation pump installed outside a reactor pressure vessel and a jet pump installed inside the reactor pressure vessel are combined to increase the power density. A so-called jet pump system is employed. Hereinafter, a jet pump of a boiling water reactor employing the jet pump system will be described. A conventional example will be described with reference to FIGS. FIG. 8 is a longitudinal sectional view showing a schematic configuration of the BWR. A coolant 2 and a reactor core 3 are accommodated in the reactor pressure vessel 1. The reactor core 3 includes a plurality of fuel assemblies and control rods (not shown), and is accommodated in a reactor core shroud 10. [0004] The coolant 2 flows through the core 3 upward.
At that time, the temperature is raised by the nuclear reaction heat of the reactor core 3 and a two-phase flow of water and steam is established. Coolant 2 in two-phase flow
Flows into the steam separator 4 installed above the reactor core 3, where it is separated into water and steam. Of these, the steam is introduced into a steam dryer 5 installed above the steam separator 4, and becomes dry steam. [0005] The dried steam is transferred to a steam turbine (not shown) via a main steam pipe 6 connected to the reactor pressure vessel 1 and is used for power generation. On the other hand, the separated water flows through the downcomer section 7 between the reactor core 3 and the reactor pressure vessel 1 and flows down below the reactor core 3. A control rod guide tube 8 is provided below the core 3.
The control rod is inserted into and pulled out of the reactor core 3 through the control rod guide tube 8. A control rod drive mechanism 9 is provided below the control rod guide tube 8, and the control rod drive mechanism 9 controls the insertion and withdrawal of the control rod into and from the reactor core 3. A plurality of jet pumps 11 are installed in the downcomer section 7 at equal intervals in the circumferential direction. On the other hand, a recirculation pump (not shown) is provided outside the reactor pressure vessel 1, and a recirculation system is provided by the recirculation pump, the jet pump 11, and the recirculation piping arranged between them. It is configured. Then, driving water is supplied to the jet pump 11 by the recirculation pump, and the coolant 2 is forcibly circulated into the core by the action of the jet pump 11. The jet pump 11 has a riser pipe 12 as shown in FIG. Riser tube
Numeral 12 is fixed to the reactor pressure vessel 1, and introduces the coolant 2 supplied from the recirculation inlet nozzle 13 of the recirculation pump into the reactor. A pair of elbows 15 (15A, 15B) is connected to the upper part of the riser tube 12 via a transition piece 14. A pair of inlet throats 17 (17A, 17B) are connected to the pair of elbows 15A, 15B via a pair of mixing nozzles 16 (16A, 16B). A diffuser 18 (18A, 18B) is connected to the pair of inlet throats 17A, 17B, respectively. Then, the coolant 2 is injected by the mixing nozzles 16A and 16b, and at that time, the reactor water is entrained from the surroundings,
The injected coolant 2 and the entrapped water are mixed in the inlet throats 17A and 17B. Thereafter, the hydrostatic head is restored by the diffusers 18A and 18B. By the way, in the above configuration, fluid vibration is generated by the flow at the time of cooling sent from the recirculation pump. To cope with this fluid vibration, the riser pipe 12 has its lower end welded to the recirculation inlet nozzle 13 as described above, and its upper end is fixed to the reactor pressure vessel 1 via the riser brace 20. The inlet throats 17A and 17B are
As described above, the upper end is mechanically connected to the transition piece 14 via the mixing nozzles 16A and 16B and the bend, and the lower end is inserted at the upper end of the diffusers 18A and 18B. As described above, both the riser tube 12 and the inlet throats 17A and 17B are configured to sufficiently cope with the fluid vibration. Next, the configuration above the mixing nozzles 16A and 16B will be described. A pair of ears 21 are formed on both sides of the transition piece 14, respectively.
Project upward, and a groove 22 is formed inside the upper end thereof. The groove 22 has a pair of jet pump beams having a rectangular cross section that increases toward the center in the longitudinal direction.
23 is fixed by fitting both ends to the groove 22. At the center of the jet pump beam 23, a screw hole (not shown) is formed in the vertical direction, and a head bolt 28 is screwed into this screw hole. A hexagonal head is formed at the upper end of the head bolt 28, and a semi-round head is formed at the lower end. On the other hand, a pedestal (not shown) having a horizontal upper end surface is formed in each of the elbows 15A and 15B, and a counterbore (not shown) is formed in this pedestal.
The semi-round head of the head bolt 28 is fitted into the counterbore through a spherical washer. Since the inlet throats 17A and 17B are not fixed to the reactor pressure vessel 1, the inflow water pressure of the driving water supplied through the riser pipe 12 acts on the upper ends and the elbows 15A and 15B. . Elbows 15A, 15
A diffuser from a nozzle (not shown) connected to the other end of B
The reaction force such as the jet pressure of the driving water jetted toward the inside of 18A and 18B acts upward. A head bolt 28 is screwed to the jet pump beam 23 to counter this load. Since the ear 21 is fixed at a fixed position, when the head bolt 28 is screwed in, the head 21 is moved above the jet pump beam 23, and both ends of the head bolt 28 contact the upper wall surface of the groove 22. It will be in contact. This causes an upward load. Conversely, a downward load is applied to the upper ends of the elbows 15A and 15B via the head bolts 28, and the magnitude thereof is determined in relation to the upward load due to the reaction force of the driving water or the like. You. A keeper (not shown) is detachably fitted to the hexagonal head of the head bolt 28. The keeper is fixed by spot welding on a support plate (not shown). The support plate has a rectangular shape and is fixed to the upper surface of the jet pump beam 23 by two bolts. The inlet throats 17A and 17B are attached to a riser blanket 25 fixed to the riser tube 12. Further, the diffusers 18A and 18B are fixed to a shroud support 26 welded to the reactor pressure vessel 1. [0018] The jet pump 11 is used under a severe condition to circulate the coolant, as compared with other devices.
For this reason, a large load acts on each member, and particularly severe stress acts on the riser brace 20 that supports the riser tube 12 in the middle. The riser brace 20 is a riser tube.
In addition to suppressing the fluid vibration generated during operation of the reactor 12, the thermal expansion difference between the reactor pressure vessel 1 made of carbon steel and the riser pipe 12 made of austenitic stainless steel is absorbed. Therefore, during the operation of the reactor, the reactor is in a deformed state while absorbing the difference in thermal expansion. In order to control the output of a nuclear power plant, it is important to measure the flow rate of the jet pump during normal operation. For this reason, measurement pipes 19 are provided above and below the diffusers 18A and 18B. The static pressure difference between the upper and lower portions of the diffuser 18 during operation is measured, and the jet pump flow rate is calculated based on the measured value and a calibration value measured before using the plant. The measurement pipe 19 is welded to a static pressure hole at the upper and lower portions of the diffuser and is welded and supported by a support 24 fixed to the diffuser 18. Further, as shown in FIGS. 10 (a) and 10 (b), a jet pump is provided. It is arranged in a complicated state at the lower part of 11, and is connected to a pipe outside the furnace via a jet pump measurement nozzle 27. The jet pump measuring nozzles 27 are provided at two target positions in the reactor pressure vessel 1. The jet pump 11 having such a configuration is used under severe conditions compared to other devices due to the flow at the time of cooling sent from the recirculation pump. For this reason, a large load acts on each member, and in particular, the measuring pipe 19 receives the influence of the fluid vibration of the diffuser 18 directly or through the support 24, so that severe stress is applied. It is fully expected that a break will occur. If the measurement pipe 19 breaks, it will hinder the power control of the reactor, and must be repaired. Here, the measurement pipe is an annular space between the reactor pressure vessel 1 and the shroud 10 as is apparent from FIG.
The riser pipe 12 and the inlet throat 17 are disposed above the instrumentation pipe 19, and the jet pump components such as the riser brace 20, the mixing nozzle 16, and the elbow 15 are disposed above the instrumentation pipe 19. . In the above configuration, for example, when a crack or break occurs in the measurement pipe 19 or the welded portion of the jet pump system due to any cause,
The repair work must be performed remotely from directly above the core, which is a high radiation control area, and it is extremely difficult to access the piping. As a means for repairing such a damaged measuring pipe 19, welding may be performed. However, since repair work is generally performed underwater, a large-scale repair device is required and a long-term repair apparatus is required. There is a problem of construction. In addition, if these works are left unchecked, the jet pump may crack further and the jet pump that controls the power of the reactor will be in such a state. It is also considered that it may have an adverse effect on objects, and there is an undesirable problem. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a piping clamp device for measuring pipes in a nuclear reactor capable of reducing stress caused by fluid vibration generated at a weld between a support at the lowermost part of a jet pump diffuser and a measuring pipe. To provide. According to the present invention, a diffuser of a jet pump provided in a reactor pressure vessel of a boiling water reactor and a support for fixing a measurement pipe by welding are provided. In a piping clamp device for measurement in a nuclear reactor for reducing stress due to fluid vibration generated at a weld between a support and a pipe for measurement, a substantially semicircular arm abutting on the outside of the diffuser, and one end of this arm or A body provided at both ends, a fixing wedge provided on the body via a tightening bolt, one end of which is inserted into the fixing wedge, and the other end of which abuts against the outer surface of the measuring pipe to be fixed. And a pressing wedge connected via a pin to the body.
Loose stop to stop the tightening bolt from coming loose
A bolt is provided . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a piping clamp device for measurement in a nuclear reactor according to the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a top view showing the clamp device according to the first embodiment, FIG. 2 is a side view showing a part of FIG. 1 in a longitudinal section, FIG. FIG. 3 is a side view showing an enlarged partial longitudinal sectional view of a part b of FIG.
In the figure, the same parts as those in FIGS. 8 to 10 are denoted by the same reference numerals. 1 to 4, reference numeral 30 denotes a semicircular arm. A body 31 is provided at one end of the arm 30, and a projection 32 is provided on the inner surface and a hanging ear 33 is provided on the upper surface at the other end. Have been. A protrusion 32 is also provided at the center of the inner surface of the arm 30. These projections 32 abut against the outer surface of the diffuser 18. The hanging ears 33 are located substantially at the center of the arm 30 and the body 31.
It is also provided on the upper surface of. As shown in FIG. 3, a fixing wedge hole 35 for inserting a fixing wedge 34, a screw hole 38 for screwing a screw portion 37 of a tightening bolt 36, and an upper shaft of the tightening bolt 36 are formed in the body 31.
An upper shaft hole 40 into which the locking bolt 39 is inserted, a screw hole 43 into which the screw portion 42 of the locking bolt 41 is screwed, and a large-diameter hole 45 into which a return member 44 of the locking bolt 41 is inserted are formed. A protrusion member 46 for preventing slipping is provided between the upper shaft 39 of the tightening bolt 36 and the screw portion 37, and a washer 48 is attached to the upper end of the tightening bolt 36 by tightening a nut 47 on the body 31. It is interposed between the end face. The washer 48 is bent downward by the lowering of the bending member 49 having the slope formed on the locking bolt 41, and the bent portion 50 suppresses the rotation of the tightening bolt 36, and the lifting member 44 raises the returning member 44. The folded portion 50 of the washer 48 is folded back to the opposite side. Reference numeral 51 denotes a stopper, which prevents the surface 52 from coming off due to contact when the locking bolt 41 is loosened, that is, when the locking bolt 41 is raised. A large V-shaped groove is provided at the tip of the fixing wedge 34.
A pressing wedge 54 is inserted into the large V-shaped groove 53 and connected by a pin 55. The pressing wedge 54 has an elongated hole 56 into which the pin 55 is inserted.
55 is slidable. A pin insertion hole 57 is also formed in the fixing wedge 34. A measuring pipe is provided at the tip of the pressing wedge 54.
A small V-shaped groove 58 is provided which is pressed against and in contact with 19.
The body 31 is provided with a finger-like support 59 that contacts the upper surface of the support 24. The support 59 is a member that applies the load of the entire clamp device to the upper surface of the support 24 that fixes the diffuser 18 and the measurement pipe 19 by welding. Since the fixing wedge 34 and the pressing wedge 54 are rotatable about the pin 55, the measurement pipe
It has a structure that closely contacts the 19 slopes. Hanging ears 33
Is used to move the diffuser 18 to a predetermined position. Next, the operation of the piping clamp apparatus for measurement in a nuclear reactor having the above configuration will be described with reference to FIGS. FIG. 5 is a configuration diagram showing a suspended state when the measuring pipe clamp device of the present embodiment is disposed in a reactor pressure vessel. As shown in FIG. 5, a cylindrical core shroud 10 is installed in the reactor pressure vessel 1, and in the core shroud 10, an upper grid plate 60 supporting the upper end of a fuel assembly (not shown) is provided. And a core support plate 61 that supports the lower portion of the fuel assembly via a fuel support (not shown). A fuel exchanger 62 is disposed above the reactor pressure vessel 1. A pole 64 is suspended from the fuel exchanger 62 via a pole handling mechanism 63. That is, the pole handling mechanism 63 is provided with a hoist 65 provided in the fuel exchanger 62.
And a wire 66 wound around the hoist 65. A pole 64 is connected to the wire 66 via a pole connection portion 67. The pole 64 has a configuration in which, for example, a plurality of poles having a fixed length are connected via a pole joint.
The lower end of the pole 64 is connected to the piping clamp device 68 for measuring in the reactor (hereinafter referred to as a clamp device) shown in FIGS. With the clamp device 68 incorporated in the jet pump diffuser 18 and the measurement pipe 19, two projections 32 provided on the inner surface of the semicircular shape 30 open on one side are formed on the surface of the diffuser 18. Contact. At the end of the arm 30, a fixing wedge 34 moves up and down by the rotation of the tightening bolt 36 and moves in the circumferential direction of the diffuser 18. The whole is fixed in contact with the diffuser 18 by contact. A pressing wedge 54 is incorporated in the fixing wedge 34 and is rotatable about a pin 55 so as to closely engage with the inclination of the instrumentation pipe 19. Next, when the jet pump measuring pipe 19 is fixedly held by using the clamp device according to the present embodiment, the following procedure is performed. First, after the reactor shuts down,
Remove the upper lid of the reactor pressure vessel 1. Thereafter, the steam dryer and shroud head are moved to the equipment storage pool and work is performed thereafter. In this case, as shown in FIG. 5, the clamp device 68 is suspended by the hoist 65 of the refueling machine 62 and is temporarily installed at a predetermined position of the jet pump diffuser 18. In this state, a pole 64 having a nut runner 69 incorporated at the lower end is hung by the wire 66 of the auxiliary hoist 65, and is seated on the head ear 33 of the elbow and turned to tighten the tightening bolt.
Rotate 36 heads. By rotating the tightening bolt 36, the fixing wedge 34 moves down, the pressing wedge 54 moves in the circumferential direction, and presses the measuring pipe 19 to diffuser.
It is fixed integrally with 18. Next, the washer 48, which has been fastened and fixed to the tightening bolt 36 with the nut 47, is loosened, and the locking bolt 41 is connected to the nut runner 69.
Rotate and lower with
The washer 48 is provided by a tapered bending member 49 provided on the
Can be bent. If the washer 48 is to be restored to the original state, the loosening bolt 41 is rotated in the reverse direction by the nut runner 69, and the washer 48 is flattened by the disc-shaped projection-like return member 44 provided below the loosening bolt 41. Then, the tightening bolt 36 can be rotated. According to such an embodiment, stress caused by fluid vibration generated in a weld between the support at the lowermost part of the jet pump diffuser installed in the reactor pressure vessel 1 and the measuring pipe 19 is reduced, and the operation rate of the plant is improved. Can be planned. In the above-described embodiment, an example has been described in which the fixing wedge 34 and the pressing wedge 54 are provided on the body 31 at one end of the arm 30. However, when a plurality of measurement pipes 19 are simultaneously fixed, A body 31 is provided at both ends of the arm 30 and a fixing wedge 34 and a pressing wedge are provided on the body 31 in the same manner as described above.
54 can also be provided. Next, a second embodiment of the clamp device according to the present invention will be described with reference to FIGS. 7 (a) and 7 (b). FIG. 7A is a top view of the present embodiment, and FIG. 7B is an elevation view of FIG. 7A viewed from the lower body side. In FIG. 7, the same reference numerals are given to the same portions or portions having similar functions in FIGS. For convenience of description, the upper end of the arm 30 will be referred to as an upper part and the lower end of the figure will be referred to as a lower part. The present embodiment differs from the first embodiment in that bodies 31a and 31b having members for pressing the measurement pipe 19 are provided at both ends of the semicircular arm 30, and the upper body 31 is provided.
A is provided with a pressing wedge 54 which makes surface contact with the measurement pipe 19, and a vertically movable holding block 74 which comes into contact with the lower body 31b by pressing the diffuser 18 is provided. That is, a wedge support 70 for supporting the pressing wedge 54 and a claw 71 mounted on the support 24 are attached to the upper body 31a of the arm 30 by bolts 72 and 73. The pawl 71 serves as a support for supporting the load of the clamp device including the arm 30 and other members. On the other hand, the lower body 31b of the arm has a support portion 74a of an arcuate holding block 74 having two projections 32 on its inner surface.
Are provided on the fixing wedge 34 movably by fitting. The fixing wedge 34 has, for example, a configuration as shown in FIGS. 1 to 4 described above, and is attached to the lower body 31b. When the tightening bolt 36 provided on the lower body 31a is tightened and rotated, the wedge 34 moves forward. When it is loosened, it retreats. A locking bolt 41 is provided adjacent to the tightening bolt 36. Reference numerals 75 and 76 are holes for lifting the clamp device. The second embodiment is different from the first embodiment in that the position where the instrumentation pipe 19 is fixed can be set in the opposite direction to the pressing wedge 54.
Hold the measurement pipe 19 with the pressing wedge 54 and tighten the
By rotating 36, the holding block 74 moves forward and comes into contact with the diffuser 18, and the measurement pipe 19 is pressed against the support 24 by the contact between the two points of the projection 32 of the holding block 74 and the pressing wedge 54 to fix the whole. be able to. The pin 55 is incorporated in the assembly of the pressing wedge 54 and the wedge support 70 so that the surface of the measuring pipe 19 can be brought into surface contact, and the fixing of the measuring pipe 19 is uniform. This has the advantage that it can be strongly fixed in any aspect and the fixing effect is increased. In the above embodiment, the washer 48 can be integrally formed with the tightening bolt 36. According to the present invention, the fluid vibration generated in the weld between the support at the lowermost part of the diffuser of the jet pump and the measuring pipe can be reliably and remotely controlled in water with the jet pump installed. It can be prevented in a short time. Also, by providing a pressing wedge at one end of the semicircular arm in surface contact with the measurement pipe, providing a holding block at the other end of the arm, and contacting the projections in the holding block with the diffuser to fix the whole In addition, the measurement pipe can be firmly fixed. Therefore, it is possible to greatly reduce the radiation exposure of the workers, to confirm the soundness of the reactor, and to operate the reactor safely, which greatly contributes to the improvement of the operation rate of the nuclear power plant. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view showing a first embodiment of a piping clamp device for measurement in a nuclear reactor according to the present invention. FIG. 2 is a side view showing a partial longitudinal section in FIG. 1; FIG. 3 is an enlarged top view showing a part a in FIG. 1; FIG. 4 is an enlarged side view of a portion b in FIG. FIG. 5 is a schematic diagram for explaining a usage state of the piping clamp device for measurement in a nuclear reactor according to the present invention in a nuclear reactor. FIG. 6 is an enlarged side view of a part C in FIG. FIG. 7A is a top view for explaining a second embodiment of a piping clamp device for measurement in a nuclear reactor according to the present invention,
(B) is an elevation view which shows the holding block and arm assembly in (a). FIG. 8 is a side view showing a partial cross section of the inside of the boiling water reactor. FIG. 9 is an enlarged perspective view of a vicinity of a jet pump for explaining a conventional piping clamp device for measurement in a nuclear reactor, and showing a partial vertical cross section. 10A is a developed view showing a state in which a measuring pipe is attached to a jet pump in the reactor pressure vessel in FIG. 8, and FIG. 10B is an arrangement state in the reactor pressure vessel of FIG. FIG. [Description of Signs] 1 ... reactor pressure vessel, 2 ... coolant, 3 ... core, 4 ... steam separator, 5 ... steam dryer, 6 ... main steam pipe, 7 ... downcomer section, 8 ... control rod guide Pipe, 9: control rod drive mechanism, 10: core shroud, 11: jet pump, 12: riser pipe,
13 ... Recirculation inlet nozzle, 14 ... Transition piece, 15
(15A, 15B) Elbow, 16 (16A, 16B) Mixing nozzle, 17 (17A, 17B) Inlet throat, 18 (18
A, 18B) ... diffuser, 19 ... measurement piping, 20 ... riser brace, 21 ... ear, 22 ... groove, 23 ... jet pump beam, 24 ... support, 25 ... riser blanket,
26 ... shroud support, 27 ... jet pump measurement nozzle, 28 ... head bolt, 29 ... annular space, 30 ... semicircular arm, 31 ... body, 32 ... protrusion, 33 ... hanging ear, 34 ... fixing wedge, 35 ... Wedge hole for fixing, 36 ... Tightening bolt, 37 ... Screw part, 38 ... Screw hole, 39 ... Upper shaft, 40 ... Upper shaft hole, 41 ... Screw-proof bolt, 42 ... Screw part, 43 ... Screw hole, 44 ... Returning member, 45 ... Large diameter hole, 46 ... Protrusion member, 47 ... Nut, 48 ... Washer, 49 ... Bending member, 50 ... Bending part, 51 ... Stopper, 52 ... Surface, 53 ... Large V-shaped groove, 54… Wedge for pressing,
55 ... Pin, 56 ... Elongated hole, 57 ... Pin insertion hole, 58 ... Small V-shaped groove, 59 ... Support, 60 ... Upper lattice plate, 61 ... Core support plate, 62
… Refueling machine, 63… pole handling mechanism, 64… pole, 65
... Hoist, 66 ... Wire, 67 ... Pole connection part, 68 ... Piping device for measurement in reactor, 69 ... Nutrunner, 70 ... Wedge support, 71 ... Claw, 72, 73 ... Bolt, 74 ... Holding block,
75, 76 ... holes for lifting the clamp device.

Claims (1)

(1) Claims 1. A diffuser of a jet pump provided in a reactor pressure vessel of a boiling water reactor and a support for fixing a measurement pipe by welding. in reactor measuring pipe clamping device for reducing the stress caused by the fluid vibration generated in the welded portion of the measurement pipe, and semicircular arm you contact the outside of the diffuser, one end or both ends of the arm Body, a fixing wedge provided on the body via a tightening bolt, one end of which is fitted into the fixing wedge, and the other end of which abuts against the outer surface of the measurement pipe to contact the fixing wedge. comprising a wedge for pressing linked via a pin, said ball
D is adjacent to the tightening bolt
A piping clamp device for measurement in a nuclear reactor, wherein a locking bolt for stopping loosening is provided .